Carbon + GFO = pH drop?

[EllisJuan]

Tonight I hooked up a BRS dual reactor that I modified and split into two separate reactors. One is running BRS carbon and one is running BRS GFO. In the last 70 minutes my pH has dropped from 8.01 to 7.92. I have never seen my pH drop that fast. Usually at the most I will see .05 swing in an hour. Has anyone else observed this? Should I be concerned?

 

[EllisJuan]

None of my livestock seems to mind. I have my alarm on my Apex set to 7.8. I hope I don't wake up in the middle of the night to my phone popping of...

 

[NanaReefer]

Not uncommon for PH to drop with the use of GFO. Especially in smaller tanks or when large quantities are used. Sometimes using less the recommended amount is required.

 

[AZDesertRat]

Yes that is common.
How much GFO did you use? NEVER use BRS recommendations for GFO amounts, they are completely out in left field compared to every other vendor on the planet. Start out with 5 grams per 10 gallons of tank water and slowly over the next 6 weeks or so work up to a maximum dose of 10 grams per 10 gallons if you see the need. 10 grams is about one level teaspoonfull so not very much media. I run 50 grams 24/7/365 in a 100G mixed reef and have good results without causing pH drop or bleaching of corals which is associated with that.

 

[EllisJuan]

It bottomed out last night at 7.86 and has risen to 7.96 currently. Maybe it was just coincidence, but I had never seen it fall that rapidly.

Yes that is common.
How much GFO did you use? NEVER use BRS recommendations for GFO amounts, they are completely out in left field compared to every other vendor on the planet. Start out with 5 grams per 10 gallons of tank water and slowly over the next 6 weeks or so work up to a maximum dose of 10 grams per 10 gallons if you see the need. 10 grams is about one level teaspoonfull so not very much media. I run 50 grams 24/7/365 in a 100G mixed reef and have good results without causing pH drop or bleaching of corals which is associated with that.

I am running BRS's recommended amount which is 1.25 cups. Before I was running 150gms of Phosban in a TLF reactor. The amounts look about the same as far as volume is concerned.

 

[kpiotrowski]

That not a big swing, but ph is on the low side to begin with. what is your run your alk at? higher alk can stabilize ph better.

 

[EllisJuan]

That not a big swing, but ph is on the low side to begin with. what is your run your alk at? higher alk can stabilize ph better.

I have not checked it in about a week. It was 9.2 then. I will check it again in a bit. As far as pH, I know it is on the low side...it has always been that way. Most days I see ~8.05 high and ~7.95 low give or take a couple hundredths.

 

[EllisJuan]

Just checked alk. It is at 8.9dkh. I use a Hanna Checker.

 

[AZDesertRat]

Way too much GFO for a 65 gallon tank which should have no more than 65 grams maximum once acclimated. Read the instructions from every other vendor, many who have been selling it a lot longer than BRS. I use BRS GFO myself along with many of their other supplements but I question some of their directions.

 

[EllisJuan]

Way too much GFO for a 65 gallon tank which should have no more than 65 grams maximum once acclimated. Read the instructions from every other vendor, many who have been selling it a lot longer than BRS. I use BRS GFO myself along with many of their other supplements but I question some of their directions.

Interesting. I ran 150gm of Phosban for the past 5 weeks with great results.

 

[AZDesertRat]

Two Little Fishies directions say a max of 150 grams per 150 gallons of water and start out with 1/2 that amount in the beginning. This is similar to most other vendors. Too much too fast and it messes with the alkalinity and pH big time. There are dozens of articles and threads confirming this on all the reef forums.

 

[EllisJuan]

I am not doubting you. TLF also says you can safely run up to 5 times their dosage but it may lower Alk. My Alk has always been between right around 9dkh so I was not concerned. Do you think my system has adapted to that much GFO because I have been running it for the past month? Would you remove some of the GFO? My pH is back up to 7.97 which is what it has been averaging this time of day. My daily light cycle is just starting.

 

[kutcha]

this is interesting i had never heard of this or had a swing in my PH and i use GFO ill have to keep this in the back of my mind if my PH drops all of a sudden